Heretofore, in order to prevent deformation of wood such as warpage, cracks, warp, expansion and contraction, or the like, caused by drying or moisturizing the wood, a polyethylene glycol (PEG) treatment, a phenol resin-impregnation treatment, an unsaturated polyester resin impregnation treatment (see Japanese Examined Patent Application, Second Publication No. S53-5722), an acetylation treatment and the like are known. However, in the aforementioned treatments, deformation of wood caused by moisture cannot be sufficiently prevented.
On the other hand, Japanese Examined Patent Application, Second Publication No. H05-6481 proposes that a lignocellulose material in which a polyvalent carboxylic acid or a derivative thereof has been impregnated is subjected to a heat treatment, and thereby, a three-dimensional network structure is formed among structural components of the lignocellulose material to improve dimensional stability of a wooden board or the like formed from the aforementioned lignocellulose material.
Japanese Unexamined Patent Application, First Publication No. H07-150131 describes a method for treating wood with a composition containing a basic nitrogen group-containing organopolysiloxane and an organic or inorganic acid salt, a liquid water-repellent substance and water.
Japanese Unexamined Patent Application, First Publication No. 2002-241744 describes an aqueous water-repellent agent for treating a base material, which contains a product produced by subjecting an alkoxy group-containing organosilicon compound and an amino group-containing alkoxysilane or a partially hydrolyzed product thereof to co-hydrolysis-condensation in the presence of an organic acid or an inorganic acid.